Sen. Harry Reid of Nevada, the top Democrat in the Senate, says he will not run for reelection

The surprise retirement of Sen. Harry Reid, the gritty top Democrat in Congress, risks unraveling perhaps the biggest accomplishment of his combative decade in leadership: keeping unruly Democrats united in support of President Obama's agenda and rebuffing an overtly divided GOP.

As recently as a few weeks ago, the former amateur boxer gave every indication he would seek reelection in 2016, despite a New Year's exercise mishap that left him nearly blinded in one eye.

On Friday, the Capitol Hill veteran called it quits, suggesting he preferred to leave a legacy while still in his prime rather than overstay his effectiveness.

“Somebody should go when they're still pretty good,” Reid said in an interview Friday morning at his home near the Georgetown neighborhood.

The 75-year-old Nevadan made it clear that he was leaving on his own terms — not because of his accident, Senate Democrats' new minority status or worries about his upcoming reelection campaign.

“I want to be remembered for when I was able to bat third or cleanup a lot of the time,” he said, sitting on a comfortable couch dressed in khakis, a gray cardigan and uncharacteristically colorful striped socks — his special sunglasses still protecting his injured eye.

For Democrats, the challenge ahead is whether the post-Reid party can tamp down the growing ideological differences between liberal and more centrist Democrats, navigate a rare transfer of party leadership, and avoid the kind of infighting that has all but paralyzed their Republican colleagues.

The timing is particularly sensitive as Democrats look toward the 2016 election, when they have a chance to regain the Senate majority after the Republican takeover this year.

Sen. Harry Reid (D-Nev.), the outgoing majority leader, skipped opening day in the new Congress on Tuesday as doctors orders kept him home following an exercise equipment accident last week.

The 75-year-old senator had promised to be back on the job after suffering broken ribs and face bones --...

Sen. Harry Reid (D-Nev.), the outgoing majority leader, skipped opening day in the new Congress on Tuesday as doctors orders kept him home following an exercise equipment accident last week.

The 75-year-old senator had promised to be back on the job after suffering broken ribs and face bones --...

(Lisa Mascaro)

There hasn't been an active campaign for the top Democratic leadership position in either the House or Senate since Reid won his current post in 2005. Eager to avoid a leadership fight, Reid promptly anointed the No. 3 Democrat, Sen. Charles E. Schumer of New York, as his successor.

“Schumer, in 22 months — if he plays his cards right — should be able to do it,” Reid said. “I said, ‘If you need my help, you got it. If I'm going to be in your way, I'll get out of your way.'”

Admired for his Wall Street fundraising skills and political savvy, Schumer has made no secret of his desire for the job. But the New Yorker's bold personality is more polarizing among Democrats than Reid's.

The long-running joke in Washington is that the most dangerous place to be is between Schumer and a television camera — leaving some wary of elevating a leader who could be seen as an East Coast version of another divisive Democrat, House Minority Leader Nancy Pelosi of San Francisco.

On the other hand, Schumer could be a natural bridge for Democrats if Hillary Rodham Clinton were to occupy the White House after 2016. She and Schumer served together for eight years when Clinton was the junior New York senator.

Reid's choice jumps over the party's current No. 2, Assistant Minority Leader Sen. Richard J. Durbin of Illinois. But an aide to Durbin said he threw his support to Schumer.

Reid's endorsement is important, but may not resolve the matter. Activists immediately began drafting liberal Sen. Elizabeth Warren (D-Mass.) for the post. Though her ascent seems to be a long shot, her influence will continue to register in the party.

Reid told Obama of his decision during a “long conversation” late Thursday. He said the men recounted their political battles together and reflected on what still needed to be accomplished before both leave office after next year's election.

“There are things we need to do,” Reid said, pointing to the military campaign against Islamic State militants, climate change and other issues.

Obama has leaned heavily on Reid to implement his policies, most notably with the passage of the Affordable Care Act in 2010. Even when Reid at times disagreed on strategy or tactics, he frequently served as a buffer for the president, protecting him from Republican attempts to undercut the administration's policies.

“Harry has become not only an ally, but a friend,” Obama said Friday in a statement. “I'm proud of all we have accomplished together, and I know the Senate will not be the same without him.”

With Reid now positioned as a lame duck for the next two years, Obama may be losing a trusted ally if the minority leader's political influence begins to wane.

At the same time, Reid's decision to bow out in 2016 could leave other senators feeling less inclined to stick to a unified party position. For Obama, that could help advance some of his priorities, such as providing the few Democratic votes he needs to pass the 12-nation Asian trade pact. The accord is opposed by most Democratic lawmakers but supported by most Republicans.

Republicans are certain to try to capitalize on the moment of potential Democratic disarray.

“Hit the road, Harry,” cheered a fundraising appeal from Tea Party Express, a political action committee.

Conservative groups had made Reid their No. 1 target last time he ran, in 2010, and intended to do so again. News of his retirement “brings us great pleasure,” the PAC said.

Reid's retirement provides Republicans with what is likely to be their best opportunity to pick up an additional Senate seat in 2016. A race that was considered close but leaning in Reid's direction suddenly has become a toss-up and will be among the most closely watched and probably hardest-fought in the country.

Nevada Gov. Brian Sandoval is the overwhelming favorite of the Republican establishment to succeed Reid, though he seems to have all but taken himself out of the race. Reid has endorsed Catherine Cortez Masto, a former state attorney general now serving as executive vice chancellor of the Nevada System of Higher Education.

Senate Majority Leader Mitch McConnell (R-Ky.) said that Reid was “underestimated often,” noting that his “distinctive grit and determined focus … continue to make him a formidable opponent today.”

Even some Democrats have bristled at Reid's tight-fisted style as Senate majority leader from 2007 to 2015, including his refusal to allow amendment votes. Reid had been increasingly blamed for Senate gridlock and dysfunction, which some Democrats said may have contributed to the party's losses in the November election.

In Washington, Reid may be most remembered for changing Senate filibuster rules to allow approval of Obama's nominees.

In the end, a man who pulled himself up from the forlorn little mining town of Searchlight, Nev., said he felt he had done all he could do.

The senator had made a preliminary decision over the Christmas holiday that he was ready to retire, an aide said, but then the accident brought out his fighting instinct. He wanted to regain his footing before moving forward with such a momentous decision.

Even with its many gray-haired statesmen, the Senate can be unkind to lawmakers who cling to office. Reid would be in his mid-80s by the time another term came to a close, and the senator, who grew up listening to radio broadcasts of baseball games and always imagined himself playing the outfield, said he didn't want to finish his career as a designated hitter.

In Nevada, Reid has left his imprint — not just on the few buildings bearing his name, but on policies to develop renewable energy resources that have sometimes caused controversy. Some credit — or blame — him for single-handedly stopping the nuclear waste dump at Yucca Mountain outside Las Vegas.

The senator said that he had no interest in becoming a lobbyist or a high-powered lawyer, but that he might write another book.

“The one thing that's not on my to-do list is: I'm not going to spend more time with my kids,” said Reid, who is known for his crusty way of saying what others may think but not express.

He said he and his wife, Landra, talk to their children every day and have a “pet peeve” about citing that reason for retirement. “We just think that's obnoxious.”